1. Field
The present disclosure generally relates to composite structures and, in particular, to the formation of composite structures. Still more particularly, the present disclosure relates to a method and apparatus for forming composite fillers used to fill channels between composite structures.
2. Background
Composite materials are tough, lightweight materials created by combining two or more functional components. For example, a composite material may include reinforcing fibers bound in a polymer resin matrix. The fibers may be unidirectional or may take the form of a woven cloth or fabric. In thermoset composites, fibers and resins are arranged and cured to form a composite material.
When composite structural members are joined together, channels or voids may be present along bond lines between the members. These channels may need to be filled in order to increase the strength of the bond. For example, in the aircraft industry, composite fuselage stiffeners may include a filler at the radius bond line between the stiffener and a fuselage skin. For example, a filler may be used at the radius bond line between a stringer and a skin panel.
In some cases, the filler takes the form of triangular cross-sectional structure which fills the voids at the bond line. This triangular cross-sectional structure is sometimes referred to as a “noodle” or a “composite filler.”
A composite filler may be formed from composite materials such as adhesive, prepreg tape, fabric, or other types of composite materials. For example, the composite filler may be formed by extruded material, rolled composite material, or stacked strips of composite material. When the composite filler has a desired level of stiffness, the composite filler may transfer some of the load from the stiffener into the base.
During manufacturing and operation of an aircraft, the composite filler may experience various forces. These forces may cause undesired inconsistencies to form within the composite filler. Examples of these undesired inconsistencies may include cracks, delamination, and other inconsistencies. In some cases, the inconsistency may spread from an outer surface of the composite filler through the interior of the composite filler.
If the composite filler includes one of these inconsistencies, the composite filler may not function to transfer loads as desired. Moreover, the composite filler with the inconsistency, as well as the structures bonded to it, may need rework. This rework may cause increased maintenance and service cost for an aircraft, increased manufacturing costs for the composite structures used in the aircraft, or both. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.